#1 - The number of elites in CO is about the same, per CO. With the 50% EQM for lower priced tickets not purchased on co.com - it is harder for a business traveler to earn CO elite status - hence the numbers are not growing. CO does not want to grow the number of elites - to allow for some benefits.
#2 - It is not just the simplified DL pricing or lower FC seats. CO.com will many times assign Y or even Z or A to a certain segment of a coach itinerary. For example, a couple of weeks ago CO - if you fare'd a flight from say DCA-EWR-SRQ or FLL or PBI for outbound on Dec. 21-22, the segment from EWR to Florida would either come out in Y or A fare - the total being about $500 RT for the holiday week (other segments in lower categories). If you specified you wanted a F ticket - the fare was over $1K. But specifying coach - the cheapest would include either A or instant upgrade for Elite Y fare in the most significant segment.
Hence - CO was filling up F on those flights from EWR to Florida - on Xmas weekend - by simply making that segment A or Y - for a fare that was basically the cheapest fare for a requested coach ticket.